Morsi supporters gather behind empty coffins during a fake funeral in the memory of protesters who died the day before.

AFP: Mahmud Hams

Egypt's prosecutor has ordered the arrest of the leaders of ousted president Mohamed Morsi's Muslim Brotherhood, charging them with inciting violence that saw 55 of their members shot dead.

Brotherhood spokesman Gehad El-Haddad said the announcement of charges against supreme leader Mohamed Badie and several other senior figures was a bid by authorities to break up a vigil by thousands of Mr Morsi supporters demanding his reinstatement.

The leaders were charged with inciting the violence which began before dawn on Monday, when the Brotherhood says its followers were fired on while peacefully praying.

The Brotherhood says police and troops "massacred" 42 of their supporters, with women and children among the dead.

But the army says terrorists provoked the shooting by attacking its troops.

The charges against the Brotherhood leaders were "nothing more than an attempt by the police state to dismantle the Rabaa protest", Mr Haddad said by telephone from the vigil at Rabaa al-Adawiya mosque in north-east Cairo.

He said some of the leaders whose arrest was being sought were at the site of the protest.

"What can we do? In a police state when the police force are criminals, the judiciary are traitors, and the investigators are the fabricators, what can one do?" he said.

In addition to Badie, prosecutors ordered the arrest of others including his deputy, Mahmoud Ezzat, and outspoken party leaders Essam El-Erian and Mohamed El-Beltagi.

Meanwhile, Mr Morsi is currently being held in a "safe place, for his safety," foreign ministry spokesman Badr Abdelatty told reporters, adding: "He is not charged with anything up till now."

His overthrow by the military a week ago, after massive protests calling for his resignation, has pushed Egypt into a vortex of violence.

New interim PM reaches out to liberals

The charges and arrest orders came as interim authorities were to start talks on forming a caretaker cabinet headed by new prime minister Hazem al-Beblawi.

Mr Beblawi, a 76-year-old economist and former finance minister, said he would start selecting ministers and would begin by meeting liberal politicians Mohamed ElBaradei and Ziad Bahaa el-Din.

Both are prominent figures in the National Salvation Front, the main secularist group that led protests against Mr Morsi.

Interim president Adly Mansour has set a timetable for elections by early next year, while appointing Mr Beblawi as prime minister and Mr ElBaradei as vice president responsible for foreign affairs.

Mr Beblawi accepted that it would be a challenge to find a cabinet line-up with universal support.

"I don't believe that anything can have unanimous approval," he said.

"Of course we respect the public opinion and we try to comply with the expectation of the people but there is always a time of choice. There is more than one alternative, you cannot satisfy all of the people."

Mr Beblawi has indicated he would be open to offering cabinet posts to Islamists, including Brotherhood figures, although it is unlikely the Brotherhood would accept.

The Brotherhood has said it will have nothing whatsoever to do with a government of what it calls a "fascist coup".